Certain applications of use of superconducting cables, such as degaussing coils, require a relatively large magnetic field to be generated over a relatively large cross-section or volume. For instance, degaussing coils of one or more superconducting cables can be wound within the hull of a ship (for example, a Navy ship or the like), covering a relatively large portion of its footprint. In such applications, one or more superconducting cables can be looped around many times, where each cable is connected to carry a relatively low electrical current of about 100 A. By increasing the number of turns in the wound coils, the current (Amperes) multiplied by the number of turns is increased, thereby increasing the magnetic field generated when an electrical current flows through the cables.
Superconducting degaussing systems have included coils in which each turn is formed by a thin superconducting tape. In such systems, many insulated superconducting tapes are bundled together and inserted into a long flexible cryostat that is installed within the ship. The inside of the cryostat and, thus, the bundle of superconducting tapes, is cooled with flowing helium gas that is cooled to cryogenic temperatures. The superconducting tapes can be relatively small and lightweight, but tend to be relatively fragile. The tapes typically have an aspect ratio that is inconvenient for cabling, in that typical tapes are flat tapes with dimensions of about 1-10 mm in width and 0.05-0.5 mm in thickness.
One of the challenges with superconducting degaussing systems is that it can be difficult to make reliable and low resistive connections between the tapes in such a way that the tapes form a continuous current loop. In such degaussing systems, all tapes may need to be electrically connected in series at both ends of the cryostat such that the current runs from tape number 1 into tape number 2, then from tape number 2 into tape number 3, etc. Each cable can have up to 20 (or more) tapes to be connected. Thus, many connections must be made, for example, in a junction box in which the superconducting tapes are soldered in series through a connecting structure.
While the number of turns of a degaussing cable can be reduced by passing higher current levels through a degaussing cable, in many contexts the higher current levels may require a high-current power supply and high-current leads that can introduce a large heat load into the cryogenic system.
Superconducting cables, such as, but not limited to Conductor on Round Core (CORC) cables, may be configured with multiple superconducting tapes that are wound in multiple phases on a former. Some of the superconducting tapes, such as, but not limited to RE-Ba2Ca3O7-δ (REBCO) (RE=rare earth) coated conductors contain a superconducting film that is located on one side of a metal substrate, with one or more resistive barrier layers between the superconducting film and the substrate. In such configurations, current may enter and exit the superconducting film from one side of the tape, following a current path with low resistance. Accordingly, in certain cases such superconducting tapes must be oriented such that the side that has the superconducting film faces the connecting structure. Additionally, the bundle of tapes in the cable can be relatively fragile, which can lead to difficulties during formation of tape connections and installation of cables.